Read the easement, IF it is an exclusive use grant to others you might not be allowed to do anything ...
IF you are it's still a Maybe....a speed bump does not in my opinion restrict the passage along the easement any more than a pot hole might....however I might take pains to,clearly mark the speed bump from both directions and check local,and state law as to any design restrictions or requirements on such bumps,( I ve seen codes as to height and at least local to me they are marked well in advance )
.if some user of the easement hits the bump too fast and messes up her BMW you are sure to get sued !
I think your solution may cause more problems than the original problem ...be careful.